Patent GB-904863-A (GB)
Title: Compositions containing cellulose compounds for photography
IPC: G03C1/04
Filed: 1958-12-04
Abstract: An aqueous composition contains gelatin and from 10-50% by weight, based on the weight of the gelatin, of hydroxyethyl cellulose, or hydroxyethyl cellulose of reduced viscosity, or of a derivative of hydroxyethyl cellulose or of hydroxyethyl cellulose of reduced viscosity containing terminal carboxylic acid, carboxylic salt, carboxylic amide or carboxylic ester groups. Light-sensitive silver halides may also be present.  Preferred compositions contain 10-15% or 23-25% by weight of hydroxyethyl cellulose, or hydroxyethyl cellulose of reduced viscosity, or of said derivatives.  Hydroxyethyl cellulose of reduced viscosity may be made by reacting hydroxyethyl cellulose with hydrogen peroxide, e.g. by heating at about 50 DEG C. for 16-17 hours an aqueous p  dispersion containing 10-30% by weight hydroxyethyl cellulose and 0,01-2% by weight of 30% by weight hydrogen peroxide.  The hydroxyethyl cellulose of reduced viscosity preferably has an inherent viscosity, measured in aqueous solution at 25 DEG C., of 0,3-1, especially 0,3-0,4.  Suitable cellulose derivatives may be formed by reaction of hydroxyethyl cellulose, which may be of reduced viscosity, with a dicarboxylic anhydride, e.g. succinic anhydride.  In addition to succinates, diglycolates, phthalates and glutarates of hydroxyethyl cellulose may also be made, and mixed ether of cellulose containing hydroxyethyl groups and carboxyalkyl groups, e.g. carboxymethyl hydroxyethyl cellulose. Hydroxyethyl cellulose, preferably of reduced viscosity and having an inherent viscosity less than 1, may be esterified with a dicarboxylic anhydride either in a pyridine system in solution in acetic acid containing sodium acetate catalyst or by dissolving the hydroxyethyl cellulose in a solvent, e.g. dimethyl formamide and esterifying with the dicarboxylic anhydride in the presence of a slight excess of a tertiary base, e.g. pyridine.  The use of a solvent permits a lower degree of esterification to be achieved and hence a lower proportion of carboxyl groups in the product, than is possible in pyridine alone.  The product can be isolated by precipitation in acetone or isopropyl alcohol, or by spray-drying.  A preferred product is made by continuing the reaction until 1g. of the product will neutralize 0,3-6 ccs. N.NaOH solution.  Derivatives containing terminal carboxylic ester groups may also be made by reacting hydroxyethyl cellulose or hydroxyethyl cellulose of reduced viscosity, with a compound containing an isocyanate group and a carboxylic ester group to form a urethan containing the carboxylic ester group. Alternatively, the product may be hydrolysed to give a derivative containing carboxylic salt groups or carboxylic acid groups, or amidated to give a derivative containing carboxylic amide groups. Alternatively, the hydrolysed product containing carboxylic salt or carboxylic acid groups may be amidated to give a derivative containing carboxylic amide groups.  The compound containing an isocyanate group and a carboxylic ester group may be a carbalkoxy methyl isocyanate, preferably carbethoxymethyl isocyanate.  Using this isocyanate, the reaction is preferably continued until the urethan ester contains 1,6% by weight nitrogen.  Examples describe the preparation of compositions containing hydroxyethyl cellulose, hydroxyethyl cellulose of reduced viscosity, hydroxyethyl cellulose derivatives containing terminal carboxylic groups made by reacting hydroxyethyl cellulose with succinic anhydride, carbethoxy methylcarbamyl hydroxyethyl cellulose, (made by reacting hydroxyethyl cellulose in dimethyl formamide with carbethoxymethyl isocyanate), carbamidomethyl carbamyl hydroxyethyl cellulose (made by reacting carbethoxymethyl carbamyl hydroxyethyl cellulose with ammonia), and carboxymethyl carbamyl hydroxy ethyl cellulose (made by hydrolysing carbethoxy methyl carbamyl hydroxyethyl cellulose with caustic potash).  For the application of the invention to photographic materials, see Group XX.ALSO:An aqueous composition contains gelatin and from 10-50% by weight, based on the weight of the gelatin, of hydroxyethyl cellulose, or hydroxyethyl cellulose of reduced viscosity, or of a derivative of hydroxyethyl cellulose or of hydroxyethyl cellulose of reduced viscosity containing terminal carboxylic acid, carboxylic salt, carboxylic amide or carboxylic ester groups.